Light emitting diode device, method of fabrication and use thereof

• US 7,847,306 B2
• Filed: 10/27/2006
• Issued: 12/07/2010
• Est. Priority Date: 10/23/2006
• Status: Active Grant

• Current Assignee: Hong Kong Applied Science And Technology Research Institute Co., Ltd.
• Original Assignee: Hong Kong Applied Science And Technology Research Institute Co., Ltd.
• Inventors: Zheng, Shengmei, Feng, Jian, Chu, Hung-Shen
• Primary Examiner(s): Louie; Wai-Sing
• Assistant Examiner(s): Jahan; Bilkis
• Application Number:
  US11/588,719
• Publication Number:
  US 20080093607A1
• Time in Patent Office: 1,502 Days
• Field of Search: 257/79, 257/82, 257/94, 257/103, 257/98
• US Class Current: 257/98
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector
• CPC Class Codes: H01L 33/483 Containers
• CPC Class Codes: H01L 33/54 having a particular shape
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

Abstract

A light emitting diode device which, in use, has its light emitting region occupying a plane substantially perpendicular to a plane occupied by the surface on which the device is mounted. The primary light emission directions of the light emitting region are parallel to the surface on which the device is mounted. The device may have both its p-type and n-type semiconductor layers passivated by a layer or layers of light transmissive materials. There is a method for fabricating and mounting such a device. A plurality of the light emitting diode devices can be used in a lighting assembly for providing a plurality of independently controllable lit regions.

Claims

1. A light emitting diode device, for mounting on a surface, comprising a semiconductor substrate having a layer of p-type semiconductor material adjoining a layer of n-type semiconductor material and a light emitting region occupying a plane between the p- and n-type materials, a light transmissive substrate on which the semiconductor substrate is formed, the light transmissive substrate having a perimeter greater than a perimeter of the semiconductor substrate, a first terminal electrically connected to the p-type semiconductor material layer and a second terminal electrically connected to the n-type semiconductor material layer, each of said terminals comprising a contact pad which overlaps with the perimeter of the semiconductor substrate and which extends to at least the perimeter of the light transmissive substrate to thereby be exposed to enable the diode device to be electrically bonded to an electrical circuit on the mounting surface, wherein the light emitting diode device is fabricated for mounting with the plane occupied by the light emitting region substantially perpendicular to a plane occupied by the mounting surface and wherein a primary light emission direction of the light emitting region is parallel to the plane occupied by the mounting surface.

2. The light emitting diode device of claim 1 wherein the p- and n-type materials are completely passivated by one or more light transmissive layers.

3. A light emitting diode device for mounting on a surface occupying a first plane and having first and second primary light emission directions parallel to the first plane, the light emitting diode device comprising:

a multi-layer semiconductor substrate comprising a first layer of a p-type semiconductor material, a second layer of a n-type semiconductor material located with the first layer forming a junction between the p- and n-type semiconductor materials and a light emission region occupying a second plane at the junction, a light transmissive substrate on which the multi-layer semiconductor substrate is formed, the light transmissive substrate having a perimeter greater than a perimeter of the multi-layer semiconductor substrate, a first terminal electrically connected to the p-type semiconductor material layer and a second terminal electrically connected to the n-type semiconductor material layer, each of said terminals comprising a contact pad which overlaps with the perimeter of the multi-layer semiconductor substrate and which extends to at least the perimeter of the light transmissive substrate to thereby be exposed to enable the diode device to be electrically bonded to an electrical circuit on the mounting surface, and

the light emitting diode device being fabricated for mounting on the surface with the second plane occupied by the light emission region substantially perpendicular to the first plane occupied by the surface.

4. The light emitting diode device of claim 3 wherein the first and second terminals are located adjacent an edge of the light emitting diode device for making electrical connection with a circuit on the surface.

5. The light emitting diode device of claim 3 further comprising a light transmissive layer located on the semiconductor substrate and wherein the semiconductor substrate is sandwiched between the light transmissive substrate and the light transmissive layer.

6. The light emitting diode device of claim 5 wherein the p- and n-type semiconductor materials are passivated by the light transmissive layer.

7. The light emitting diode device of claim 5 wherein the light transmissive layer has a refractive index substantially similar to the refractive index of the light transmissive substrate.

8. The light emitting diode device of claim 3 further comprising a substantially light transmissive layer located at or adjacent the semiconductor substrate and having a first surface facing the semiconductor substrate and an opposed second surface, and

a reflective surface formed at or adjacent the second surface of the light transmissive layer for directing at least a portion of emitted light in a direction away from the first emission direction so as to enhance light emission in the second emission direction.

9. The light emitting diode device of claim 8 wherein the reflective surface is patterned to allow at least a portion of the light to propagate through the reflective surface.

10. The light emitting diode device of claim 3 further comprising a substantially light transmissive layer located at or adjacent the semiconductor substrate and having a first surface facing the semiconductor substrate and an opposed second surface, and

a mask formed at or adjacent the second surface of the light transmissive layer for directing at least a portion of emitted light in the first emission direction, wherein the mask is patterned to allow at least a portion of the light to propagate through the mask.

11. An edge-mount light emitting diode device, for mounting on a surface, fabricated from a semiconductor substrate such that in use a light emitting region of the device defined in the semiconductor substrate occupies a plane substantially perpendicular to a plane occupied by the mounting surface, the light emitting region of the device being totally passivated by at least one light transmissive layer having a perimeter greater than a perimeter of the semiconductor substrate such that light from said light emitting region emits into said at least one light transmissive layer in at least two opposing directions parallel to a plane occupied by said mounting surface, wherein contact pads of electrically conductive terminals connected to respective p-type and n-type layers of the semiconductor substrate which define the light emitting region extend to at least the perimeter of the at least one light transmissive layer to thereby be exposed to enable the diode device to be electrically bonded to an electrical circuit on the mounting surface.

12. The edge-mount light emitting diode device of claim 11, wherein the p-type and n-type semiconductor layers are passivated by the light transmissive layer.

13. The edge-mount light emitting diode device of claim 11 comprising a reflective or opaque mask located at or adjacent a first light emission direction of the light emitting region for at least partially reflecting, re-directing and/or blocking light emissions in the first direction and/or enhancing light emissions in another, second, direction.

14. A lighting assembly for providing a plurality of independently controllable lit regions, comprising:

a mounting surface for mounting a plurality of light emitting diode devices, and

a plurality of light emitting diode devices fabricated for mounting to the mounting surface with a plane occupied by light emitting regions of the devices substantially perpendicular to a plane occupied by the mounting surface such that light emissions of the light emitting regions are parallel to the plane occupied by the mounting surface, wherein the plurality of light emitting diode devices are arranged on the mounting surface so that each light emitting device contributes light emissions to at least two opposed lit regions and wherein each light emitting device is fabricated from a semiconductor substrate such that a light emitting region of said device defined in the semiconductor substrate is totally passivated by at least one light transmissive layer having a perimeter greater than a perimeter of the semiconductor substrate, wherein contact pads of electrically conductive terminals connected to respective p-type and n-type layers of the semiconductor substrate which define the light emitting region extend to at least the perimeter of the at least one light transmissive layer to thereby be exposed to enable the diode device to be electrically bonded to an electrical circuit on the mounting surface.

15. The lighting assembly of claim 14 wherein the light emitting diode devices comprises red light emitting devices, green light emitting devices and blue light emitting devices and wherein the light emitting devices are arranging on the mounting surface so that at least one red, one green and one blue light emitting device contributes light emissions to each lit region.

16. The lighting assembly of claim 14 wherein the light emitting diode devices are arranged in a grid or hexagon pattern on the mounting surface.

17. The lighting assembly of claim 14 used as a backlight for a liquid crystal display panel and having a plurality of independently controllable lit regions for providing backlighting to a corresponding plurality of division areas of the liquid crystal display panel.

18. A light emitting diode device, for mounting on a surface, comprising a semiconductor substrate having a layer of p-type semiconductor material adjoining a layer of n-type semiconductor material and a light emitting region occupying a plane between the p- and n-type materials, wherein the light emitting diode device is fabricated for mounting with the plane occupied by the light emitting region substantially perpendicular to a plane occupied by the mounting surface and wherein the light emitting region of the device is totally passivated by at least one light transmissive layer such that light from said light emitting region emits into said at least one light transmissive layer in at least two opposing directions, wherein the at least one light transmissive layer has a perimeter greater than a perimeter of the semiconductor substrate and contact pads of electrically conductive terminals connected respectively to the p-type and n-type layers of the semiconductor substrate extend to at least the perimeter of the at least one light transmissive layer to thereby be exposed to enable the diode device to be electrically bonded to an electrical circuit on the mounting surface.

19. An edge-mount light emitting diode device, for mounting on a surface, fabricated such that in use a light emitting region of the device occupies a plane substantially perpendicular to a plane occupied by the mounting surface, wherein the semiconductor substrate has first and second terminals for powering said light emitting region, each of said terminals comprising a contact pad which overlaps with a perimeter of the semiconductor substrate, the edge-mount light emitting diode device including a light transmissive substrate on which the semiconductor substrate is formed, the light transmissive substrate having a perimeter greater than a perimeter of the semiconductor substrate, wherein contact pads of each of said terminals extend to at least the perimeter of the light transmissive substrate to thereby be exposed to enable the diode device to be electrically bonded to an electrical circuit on the mounting surface.